Controlled release materials

ABSTRACT

The invention relates to polymers whose water solubility may be triggered by changes in pH, salt concentration, concentration of surfactant or a combination of both. The polymer is a copolymer or terpolymer containing from 2 to 60 mole percent of an amine functionality that has been neutralized with a fixed acid. Specifically films formed from these polymers will be insoluble at a higher pH, but will become soluble at a lower pH. The polymers are also insoluble at a higher salt concentration, but become soluble at a lower salt concentration. The polymers can be used to coat or encapsulate active ingredients, that are released based on changes in the environment, such as in the rinse cycle of a dishwasher or laundry washing machine.

FIELD OF THE INVENTION

This invention relates to polymers whose water solubility may betriggered by changes in pH salt or surfactant concentration, or acombination of both. Specifically films formed from these polymers willbe insoluble at a higher pH, but will become soluble at a lower pH. Thepolymers are also insoluble at a higher salt concentration, but becomesoluble at a lower salt concentration. The pH and salt concentrationwhere the solubility changes, can be adjusted by controlling the typesand amounts of monomers in the polymer. The polymer is a copolymer orterpolymer containing from 2 to 60 mole percent of a protonated aminefunctionality which has been neutralized with a fixed acid.

BACKGROUND OF THE INVENTION

In many processes, different ingredients are most effective whenintroduced at specific points in the operation. For instance, rinse-aidsor fragrances are more effective when released into the rinse cycle,rather than in the wash cycle, of a dishwashing or laundry process. Onemethod to introduce an ingredient at a set time in the process would beto physically add it to the system when needed. Subsequent additions toa system are often not practical. Another method is to coat,encapsulate, or in some way protect the ingredient during the initialphases of an operation, then have the ingredient released at a givenpoint due to a change in the environment triggering the removal of theprotective barrier. These controlled release technologies allow allingredients to be added to a system at one time, but released whentriggered at different points in the operation. The trigger could be achange in the pH, salt concentration, or other environmental change.

WO 00/06684 describes a dishwasher detergent tablet, containing anencapsulated ingredient, where the coating has a solubility thatincreases with a declining concentration of a specific ion in thesurrounding medium. Preferably the coating is an amine-containingpolymer.

WO 00/17311 describes encapsulated detergent particles having a delayedrelease. The material coated is coated with a material that is insolublein a wash solution having a pH of 10 or greater, yet soluble in a washsolution of pH 9 or less. As the wash cycle progresses, the wash pHdecreases, protonating the coating material, making it more positivelycharged, and thus more water soluble. The increased water solubilityallows the coating material to break down, releasing materials that hadbeen encapsulated. The preferred encapsulating materials are amines,including polymeric amines.

U.S. Pat. No. 7,063,895 describes hydrophobically modified polymers ofmethyl methacrylate and dimethylaminopropyl methacrylate neutralizedwith acetic acid. The copolymer is exemplified for use as a controlledrelease agent.

The problem with these approaches to controlled release is that it isdifficult to control the rate of dissolution of unneutralized aminematerials in various pH ranges. Many amines are hydrophilic in natureeven when unprotonated. This results in undesirable levels ofdissolution of unneutralized amine materials even at higher pHs.Conversely, if the amine material is made more hydrophobic, it isdifficult for water to penetrate films at neutral pH's. This results ina material that is not triggerable. Furthermore, these unneutralizedamine materials will only be slightly protonated at both neutral andhigh pH in systems of low buffering capacity. This results in materialswith either no solubility and trigger, or materials with an unacceptablyslow, ill-defined trigger.

Surprisingly it has been found that a copolymer containing an aminefunctionality that is neutralized with a fixed base can form atriggerable protective layer on a material, releasing the material in acontrolled manner at a given set of environmental pH and saltconcentrations. The present invention has a very sharp and controllabletrigger compared to the materials above which would not work in lowbuffering capacity systems such as detergent systems.

While not being bound by any particular theory, it is believed thatafter film formation, the copolymers of the present invention form ahydrophobic-hydrophilic material. The hydrophilic sections are theprotonated amine monomer. The balance of the hydrophobic and hydrophiliccharacter controls the triggering of the solubility. In alkaline water,the surface protonated amine groups on the film become deprotonated bythe base present in the alkaline water. This reduces the surfacesolubility to the point where the polymer film cannot become swollen bythe water and thus cannot dissolve. The hydrophobic comonomer aids inpreventing swelling of the film. A significant amount of protonatedamine groups remain in the interior of the film even in alkaline water.They are protected by the hydrophobic nature of the film and the factthat the surface protonated amine groups have become deprotonated (i.e.,the film doesn't swell enough for the base in the water to penetrate thefilm and neutralize the interior protonated amine groups). Greater ionicstrength also aids in not allowing swelling of the film. When the filmis then placed in lower pH water, for example neutral water, there isless base present in the water and the film is much easier to swell dueto some surface ionization at the lower pH. The water can then penetratethe film. The protonated amines in the interior of the film allow thepolymer to then be dissolved in water.

Unneutralized amines with poor water solubility will not show a sharptrigger in systems of low buffering capacity. If these amines areneutralized with a volatile acid, no protonated amine will remain in thefilm after cure, resulting in films that are insoluble in all pHconditions. Conversely, if a water soluble amine is used, it will notshow a trigger, since it will be soluble at every pH.

SUMMARY OF THE INVENTION

The present invention relates to a solid polymer film comprising apolymer comprising

-   -   a) 2 to 60 mole percent of protonated amine monomer units,        wherein said protonation is formed by a fixed acid; and    -   b) 40 to 98 mole percent of hydrophobe monomer units.

The solid polymer film may be used to coat or encapsulate many types ofmaterials. The polymer coating may be triggered to become soluble inaqueous media at a given set of environmental conditions including pH,ionic strength, surfactant concentration and temperature. When thepolymer film is triggered and becomes soluble, the coated orencapsulated material is exposed to—or released into the environment.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a copolymer containing from 2 to 60mole percent of protonated amine monomer units, and 40 to 98 molepercent of a hydrophobe. The amine monomers are protonated with a fixedacid. The polymer film can be used as a protective coating for amaterial, and can be removed by increasing the solubility of thecopolymer through a change in the environment such as a change in pH,salt concentration, and other factors.

The protonated amine polymer is formed from one or more amine-functionalmonomers that are at least partially neutralized with a fixed acid. Theamine monomer is an unsaturated monomer containing an aliphatic oraromatic amine group. The amine monomer includes mono-, di-, tri-, andmulti-amines. Examples of such aliphatic amine-containing monomersinclude, but are not limited to, N,N-dialkylaminoalkyl(meth)acrylate,N,N-dialkylaminoalkylacrylate, N,N-dialkylaminoalkyl(meth)acrylamide andN,N dialkylaminoalkylacrylamide, where the alkyl groups areindependently C₁₋₁₈. These includeN-(3-dimethylaminopropyl)methacrylamide,N-(3-dimethylaminopropyl)acrylamide,N-(2-dimethylaminoethyl)methacrylate,N-(2-diethylaminoethyl)methacrylate, N-(2-dimethylaminoethyl)acrylate,N-(2-t-butylaminoethyl)methacrylate, andN-(3-morpholinopropyl)acrylamide, N-(2-diethylaminoethyl)methacrylate,N-(2-dimethylaminoethyl)acrylate, N-(3-dimethylaminoethyl)acrylate,Examples of useful aromatic amine monomers include vinyl pyridine,1-vinylimidazole, 2-vinylpyridine, and 4-vinylpyridine. Furthermore,monomers such as vinyl formamide, vinyl acetamide, and the like whichgenerate amine moieties on hydrolysis may also be used. Preferably themonomer is N-(2-dimethylaminoethyl)methacrylate,N-3-dimethylaminopropyl)methacrylamide, or a mixture thereof. Mostpreferably, the amino-functional monomer isN-(2-dimethylaminoethyl)methacrylate orN-(2-dimethylaminoethyl)acrylate.

The protonated amine-functional monomer(s) is present in the polymer atfrom 2 to 60 mole percent, preferably from 5 to 40 mole percent.Non-protonated amines may be present as hydrophobic comonomers, and mayinclude the same amines that are unneutralized. The hydrophobic(non-protonated) amines may also include amine derivatives, such asquaternized amines, N-oxides and alkoxylated amines. The total amount ofamine monomers, both protonated and un-protonated, that are present inthe copolymer is from 5 to 100 mole percent, preferably 10 to 40 molepercent, and most preferably 10 to 20 mole percent.

The amine functional monomer(s) of the copolymer are at least partiallyneutralized with a fixed acid to form th e protonated amines. A fixedacid, as used herein, refers to an acid that is not removed from thepolymer film during formation of the film or upon curing of the film. Inthis manner, the amine groups remain protonated. Examples of fixed acidsinclude, but are not limited to hydrochloric acid, phosphoric acid,sulfuric acid, lactic acid and benzoic acid and mixtures thereof.Monofunctional acids are preferred, although small amounts ofmultifunctional acids can also be used in combination. A fixed acid isdifferent than a volatile acid, such as acetic acid, which will beremoved from the film during film formation or curing for 10 min at 130C. When a volatile acid is removed, free amine groups are generated. Theamine groups may be neutralized with a combination of volatile andnon-volatile acids, provided at least 2 mole percent of the amine groupsare neutralized with fixed acid.

The amine-functional monomer can be polymerized with one or morehydrophobic comonomers to form a copolymer or terpolymer. As usedherein, a hydrophobic monomer is a monomer which forms a homopolymer ofsimilar molecular weight to the copolymer of the invention, and which isinsoluble in water. Insoluble in water, as used herein, means that lessthan 1 percent of the polymer dissolves in refluxing water after onehour. The monomer itself may be water-soluble as long as the polymerizedform is insoluble in water. The comonomer can be the amino-functionalmonomer if the amino-functional monomer forms water insoluble polymersin the unneutralized state. Useful comonomers are hydrophobic monomersincluding, but not limited to, (meth)acrylates, maleates,(meth)acrylamides, vinyl esters, itaconates, styrenics, unsaturatedhydrocarbons and acrylonitrile, nitrogen functional monomers, vinylesters, alcohol functional monomers, unsaturated hydrocarbons, andC₈-C₂₂ alkoxylated (meth)acrylates. Preferred hydrophobic monomers arevinyl monomers and acrylate monomers such as methyl methacrylate, ethylacrylate, and butyl acrylate.

Crosslinking monomers may also be present in the copolymer in smallamounts. While a polymer without any crosslinking monomers is apreferred embodiment of the invention, another preferred embodiment isthe addition of some crosslinking monomer. Some slight ioniccrosslinking may decrease the swelling of the films under certaincircumstances like higher temperatures, while not making the filmscompletely insoluble.

Small amounts of hydrophilic monomer may also be used to form thecopolymer, provided the hydrophobic portions of the polymer remain waterinsoluble.

The copolymer contains from 40 to 98 mole percent of the hydrophobicmonomer, and preferably at least 60 mole percent.

The copolymer preferably has a weight average molecular weight of under100,000, preferably from 10,000 to 50,000, and most preferably from20,000 to 40,000. The aqueous polymer composition of the invention is asolution, as opposed to a latex or emulsion polymer.

The polymers of the present invention may be synthesized by solutionpolymerization of at least one acid-neutralizable amine-functionalmonomer in a non-aqueous solvent, to form a non-aqueous polymersolution. Optionally, the polymer may be a copolymer containing one ormore hydrophobic monomers. The copolymer is synthesized by solutionpolymerization. As described in U.S. patent application Ser. No.09/690,387, incorporated herein by reference. The process involvespolymerizing at least one amine-functional monomer and at least onehydrophobic ethylenically unsaturated monomer in a non-aqueous solvent;forming an aqueous polymer dispersion from said non-aqueous polymersolution; and adding an fixed acid to at least partially neutralize thecopolymer. The addition of the acid can occur either before, after, orduring the formation of the aqueous polymer dispersion from thenon-aqueous polymer solution.

The polymers formed from this type of process are generally randomcopolymers. However, other polymer architectures such as block, star etcmay also be used. The special techniques used to synthesize thesevarious types of polymer architecture are well known in the art.

The polymerization of the monomers in a non-aqueous solvent can be doneby any means known in the art. The solvent should be miscible withwater. Preferably the solvent is capable of forming an azeotrope withwater. Examples of solvents useful in the present invention include, butare not limited to, alcohols such as methanol, ethanol, and isopropylalcohol; glycol ethers; and acetone. If the solvent is a low boilingsolvent, such as an alcohol or acetone, it may be stripped from thesolution.

Formation of the aqueous polymer dispersion from the non-aqueous polymersolution can occur by several means. First is by the addition of water,or aqueous acid, to such an extent that the weight of water in thecomposition becomes greater that the weight of non-aqueous solvent.Second is by the addition of water or aqueous acid, plus a stripping offof the solvent or an azeotrope of the solvent. In whatever means theaqueous polymer solution is formed from the non-aqueous polymersolution, the result is a solution containing at least 50 percent water,based on the total weight of water and non-aqueous solvent. The finalaqueous polymer composition is a dispersion.

The environmental conditions at which the copolymer will change frominsoluble to soluble, or trigger, are dependent on the levels ofprotonated amino monomer, the level of hydrophobic comonomer, the Tg ofthe material, and the molecular weight of the material. These factorscan be adjusted to provide a polymer film that can be triggered at theoptimal environmental conditions for release of the coated orencapsulated material. In general, the polymer will become harder toswell at lower protonated amine levels, higher hydrophobic comonomer,higher Tg, and higher molecular weight. As the polymer becomes harder toswell, it will require less salt to remain insoluble. As the polymerfilm becomes harder to swell, the pH at which the polymer will triggerbecomes lower. It is important to properly balance the properties toobtain a polymer that is triggerable. If the polymer has too muchhydrophobic monomer, too little protonated amine monomer, or too high amolecular weight, the polymer will become insoluble even under lower pHconditions). Conversely, if the polymer has too little hydrophobiccomonomer, too much protonated amine monomer, too low a Tg, or too low amolecular weight, the polymer film become hydrophilic and easy to swell,thereby only insoluble only at very high pH or very high salt.

The protonated amine polymers are useful in controlled releaseapplications. Controlled release applications are ones in which thepolymer of the invention is coated onto a material, or the material isencapsulated or physically trapped within the polymer. The solubility ofthe polymer is triggered at a certain set of environmental conditions.Once the coating solubility is triggered, it dissolved, and releases thematerial into the aqueous environment.

The polymer is insoluble in water at a certain pH, but is soluble at alower pH. The pH at which the transition from insoluble to solubleoccurs can be adjusted by modifying the types and amounts of monomers inthe polymer, the molecular weight, and degree of neutralization, asdescribed above. The polymers are also insoluble at high salt orsurfactant concentrations, and become soluble at lower salt orsurfactant concentrations. The combination of these effects appears tobe more than cumulative and makes the trigger sharper and more defined.

The material that is coated or encapsulated may be an active ingredient,a mixture of active ingredients, or a solid material such as zeolite,porous microbeads, starch, or other such material onto which an activeingredient or ingredients has been absorbed.

Materials can be coated or encapsulated by any method known in the art,such as, but not limited to, spraying or brushing the polymer onto thematerial, immersing the material in the polymer dispersion, andfluidized bed application. The type of material coated, and the type oftriggerable coating applied depends on the end-use application, and thepoint (environmental trigger or triggers) at which the material is to bereleased. The polymer coating is present on the coated/encapsulatedmaterial at a weight ratio of polymer to encapsulated material of from5:95 to 95:5. The thickness of the dry polymer film depends on the enduse. In some cases, a thin film will be sufficient, while in the case ofa sachet which will be exposed to more abrasion, a much thicker filmwill be desired. Preferably the dry film has a thickness of 1-5 mil. Thepolymer composition used to coat/encapsulate a material may beformulated with co-additives or co-resins, provided the polymer'scomonomer composition, Tg, and molecular weight is adjusted to accountfor any hydrophilicity or plasticization from the additive or resinadded.

One specific application involves the encapsulation of laundry detergentand automatic dishwasher active ingredients, for protection during thewash cycle, but for delivery during the rinse cycle. The encapsulatedactive ingredients include, but are not limited to, one or more of thefollowing: rinse aids, fragrances, anti-wrinkling aids, one or moresurfactants, builders, ion exchangers, alkalis, anticorrosion materials,antiredeposition materials, optical brighteners, fragrances, dyes,chelating agents, enzymes, whiteners, brighteners, antistatic agents,sudsing control agents, solvents, hydrotropes, bleaching agents,perfumes, bleach precursors, water, buffering agents, soil removalagents, soil release agents, softening agents, opacifiers, inertdiluents, buffering agents, corrosion inhibitors, graying inhibitors,and stabilizers. Since the wash water pH tends to be greater than pH 9,and the ionic strength tends to be greater than 0.001 to 0.01 percent byweight of salt and surfactant, the polymer films are insoluble, forminga protective barrier for the active ingredients. In the rinse cycle,where the pH is typically 6-8 and the salt and surfactant concentrationsare lower by a factor of 50 to a 100, the polymer becomes soluble,releasing the encapsulated ingredients into the water.

The protonated amine polymers are useful in many other applicationsrequiring a protective coating at higher pH and/or ionic strength, butthe release of the encapsulated or coated material at lower pH and/orionic strength. Such applications include, but are not limited to, thosedescribed and illustrated below. One of skill in the art will recognizemany other applications for which these polymers are useful astriggerable protective coatings.

The polymer may be used as a coating for pills. The coating will notdissolve in the mouth, but will dissolve at the lower pH found in thestomach, releasing the active material. In a similar manner, cleaningactives could be encapsulated and released in a controlled manner in atoilet bowl. Nutrients and weed killers may be encapsulated forcontrolled release in agricultural applications. The copolymer couldencapsulate an organic liquid, such as a fragrances, for release under agiven set of conditions.

The protonated amine copolymer is useful for encapsulation of materialsin a liquid detergent where the solid materials are suspended in theliquid detergent. The coating is insoluble due to the ionic strength,high surfactant concentration, and high pH of the liquid detergent. Thecoating could be designed to disintegrate either as the liquid detergentis diluted in the wash water or to disintegrate later in the rinse cycleby modifying the key characteristics of the polymer film. Shampoo, bodywash and other personal care products could be formulated with activesencapsulated with the protonated amine polymers.

Sachets and microcapsules made of the copolymer film could contain aliquid detergent, and would remain insoluble to the detergent due to thehigh salt level and high pH. The sachet would then disintegrate when youput the microcapsule or sachet into the wash water. This could be forliquid tablets in dishwash or for laundry detergent. Microcapsulescontaining active ingredients could be formulated into liquid detergentsfor laundry or dishwash applications, as well as shampoo and bodywashapplications. The encapsulated active ingredient(s) would be protectedfrom reaction with other ingredients in the detergent, shampoo, orbodywash, yet when diluted in-use, the actives would be released. Thiscould be useful, for example, in a shampoo/conditioner having anencapsulated conditioner, where the conditioner would not be releaseduntil the shampoo was diluted, thus allowing the conditioner to work onthe hair after the shampoo.

The microcapsules of encapsulated actives, or actives adsorbed ontoinert solids, could be made large enough to be visible, adding anattractive visual effect of suspended capsules in a personal caseformulation.

The following non-limiting examples illustrate further aspects of theinvention.

Example 1

To a 2-L flask equipped with a condenser, overhead paddle mixer andthermometer was added 282 g of isopropanol. The isopropanol was heateduntil a steady reflux was obtained. After 10 minutes under refluxconditions, a monomer mixture of 80 g of butyl acrylate (BA), 80 g ofmethyl methacrylate MMA), and 40 g ofN-[(3-(dimethylamino)propyl]methacrylamide] (DMAPMA) was added to theflask from an addition funnel over 3 hours. Simultaneously, 1.5 g of2,2′-azobis(methylbutyronitrile (Vazo 67) in 20 g of isopropanol wasadded over 3.5 hours. The materials were stirred at reflux using thepaddle mixer during the two additions. At the end of 3.5 hours, thereaction mixture was held at reflux for 30 minutes and then half of theisopropanol was removed using a Dean-Stark trap. After half of thesolvent was removed 18.27 g of HCl (38%) in 700 g of water was addedwith good agitation. After dissolution of the polymer, the remainingisopropanol was removed using the Dean-Stark trap. The solution wascooled to 30° C. and the polymer was obtained as a slightly hazy aqueoussolution.

Examples 2-6

The examples below were carried out as in Example 1 using the monomerratios and the acid neutralization levels listed in Table 1. DMAEMA isN-2-dimethylaminoethyl methacrylate.

TABLE 1 Summary of Examples 1-6 Mass Mass Glacial Mass Mass Amino Fixed% Fixed Acetic Example BA Mass MMA Monomer Acid Neutralization Acid 1 8080 40 DMAPMA 18.3 HCl 80 0 2 85 85 30 DMAPMA 13.7 HCl 80 0 3 100  70 30DMAPMA 14.7 HCl 85 0 4 120  50 30 DMAPMA 14.7 HCl 85 0 5 80 80 40 DMAEMA19.8 HCl 80 0 6 80 80 40 DMAEMA 14.9 HCl 60 6.11

Comparative Example 1

To a 3-L flask equipped with a condenser, overhead paddle mixer andthermometer was added 1082 g of deionized water, 100 g ofN-[(2-(dimethylamino)ethyl]methacrylate, 121.8 g of methanol, and 67.3 gof acetic acid. The material was sparged for 0.5 h, and then the mixturewas heated to 40° C. Once the mixture reached this temperature, asolution of 0.25 g of ammonium persulfate in 9.4 g of water was chargedto the reaction mixture. The mixture was stirred for 3 hours, and then asolution of 0.31 g of ammonium persulfate in 11.2 g of water was chargedto the flask. The reaction mixture was held at 40° C. for an additional3 hours and then cooled to room temperature and discharged.

Comparative Example 2

To a 2-L flask equipped with a condenser, overhead paddle mixer andthermometer was added 286 g of isopropanol. The isopropanol was heateduntil a steady reflux was obtained. After 10 minutes under refluxconditions, a monomer mixture of 80 g of butyl acrylate, 80 g of methylmethacrylate, and 40 g of N-[(3-(dimethylamino)propyl]methacrylamide wasadded to the flask from an addition funnel over 3 hours. Simultaneously,2 g of 2,2′-azobis(methylbutyronitrile (Vazo 67) in 20 g of isopropanolwas added over 3.5 hours. The materials were stirred at reflux using thepaddle mixer during the two additions. At the end of 3.5 hours, thereaction mixture was held at reflux for 30 minutes and then half of theisopropanol was removed using a Dean-Stark trap. After half of thesolvent was removed 14.1 g of acetic acid in 654 g of water was addedwith good agitation. After dissolution of the polymer, the remainingisopropanol was removed using the Dean-Stark trap. The solution wascooled to 30° C. and the polymer was obtained as a slightly hazy aqueoussolution.

Comparative Example 3

To a 1-L flask equipped with a condenser, overhead paddle mixer andthermometer was added 110.0 g of isopropanol. The isopropanol was heateduntil a steady reflux was obtained. After 10 minutes under refluxconditions, 101.01 g of N-[(2-(dimethylamino)]methacrylate was added tothe flask from an addition funnel over 3 hours. Simultaneously, 1.25 gof 2,2′-azobis(methylbutyronitrile (Vazo 67) in 40 g of isopropanol wasadded over 5 hours. The materials were stirred at reflux using thepaddle mixer during the two additions. At the end of 5 hours, thereaction mixture was held at reflux for 1 hour and then half of theisopropanol was removed using a Dean-Stark trap. After half of thesolvent was removed 29.27 g of acetic acid in 50 g of water was addedwith good agitation. After dissolution of the polymer, the remainingisopropanol was removed using the Dean-Stark trap. An additional 200 gof water was added during the distillation. The solution was cooled to30° C. and the polymer was obtained as yellow transparent solution.

Examples 7-15

Film solubility in detergent wash water and deionized water were tested.A film of each aqueous polymer solution in Table 1, and the threecomparative Examples was made and allowed to dry at room temperature.The films were then cured at 130 C. for 5 minutes. Approximately0.01-0.02 grams of film were then weighed using an aluminum pan. Thefilms were then placed in 2 oz. jars. The jars were filled with 50 gramsof a solution of 1.1 g of powdered Tide in 1 L of tap water (washwater). The jars were shook at room temperature using a mechanicalshaker at a low setting for 5 minutes. The solutions were then filteredthrough Whatman Grade 226 filter paper and any film pieces wererecovered. The film appearance was noted (see FIG. 1). At that point,the films were placed in the aluminum pans and dried for 15 minutes at130 C. and re-weighed. In separate experiments, the film pieces wereplaced into 50 grams of deionized water after the Tide shakingprocedure. The jars of deionized water were shook for 10 minutes. Thesolution was then filtered through a 200 mesh metal screen, and thescreen was dried for 15 minutes at 130 C. The mass of remaining film wasthen determined. The results are summarized in Table 2. Alternatively,the films were placed in 400 grams of deionized water and allowed to sitwith minimal agitation for 10 minutes (see FIG. 2).

TABLE 2 Detergent Solubility Tests. Mole % Polymer Protonated %Insoluble % Insoluble Example Sample Amine in Film Detergent DI Water 71 11.34 99.0 5.3 8 2 8.35 88.8 30.8 9 3 9.05 92.6 0 10 4 9.29 93.0 0 115 12.13 90.8 0 12 6 9.10 90.7 0 13 Comparative 0 100 100 Example 1 14Comparative 0 100 100 Example 2 15 Comparative 0 0 0 Example 3

1. A solid polymer film having water solubility triggered by change inpH, salt or surfactant concentration, or both, of an aqueous environmentin which said solid polymer is immersed, said polymer comprising: 5 to40 mole percent of protonated amine monomer units, wherein saidprotonation is formed by a fixed acid; and at least 60 mole percent ofhydrophobic monomer units, wherein the polymer film has a thickness of 1to 5 mil.
 2. The polymer film of claim 1 wherein said hydrophobe monomerunits comprise non-protonated amine monomer units.
 3. The polymer filmof claim 1 comprising from 5 to 100 mole percent of at least one aminemonomer, including both protonated and non-protonated amines.
 4. Thepolymer film of claim 3 comprising from 10 to 40 mole percent of atleast one amine monomer, including both protonated and non-protonatedamines.
 5. The polymer film of claim 4 comprising from 10 to 20 molepercent of at least one amine monomer, including both protonated andnon-protonated amines.
 6. The polymer film of claim 1 wherein said fixedacid comprises at least one monofunctional acid.
 7. The polymer film ofclaim 1 wherein said hydrophobic monomer comprises (meth)acrylates,maleates, (meth)acrylamides, vinyl esters, itaconates, styrenics,unsaturated hydrocarbons and acrylonitrile, nitrogen functionalmonomers, vinyl esters, alcohol functional monomers, unsaturatedhydrocarbons, and C₈-C₂₂ alkoxylated (meth)acrylates.
 8. The polymerfilm of claim 7 wherein said hydrophobic monomers comprise methylmethacrylate, ethyl acrylate, and butyl acrylate.